title: Enzymes that control the conversion of L-tryptophan-nicotinamide and the urinary excretion ratio (N(1)-methyl-2-pyridone-5-carboxamide + N(1)-methyl-4-pyridone-3-carboxamide)/N(1)-methylnicotinamide in mice.
abstract: There is little information on L-tryptophan→nicotinamide metabolism in mice. In the present study, we investigated the two important nutritional factors involved in metabolism L-tryptophan→nicotinamide; one is the amount of nicotinamide synthesized from L-tryptophan, and the other is the urine ratio (N(1)-methyl-2-pyridone-5-carboxamide + N(1)-methyl-4-pyridone-3-carboxamide)/N(1)-methylnicotinamide. The order of the percentages of nicotinamide synthesized from L-tryptophan was as follows: CBA strain mice (conversion percentage 0.41%) < BALB strain mice (0.82%) < C57BL/6 strain mice (1.13%) < ICR strain mice (1.70%). Urinary excretion of quinolinic acid was correlated with urinary excretion of the sum of nicotinamide and its catabolites (p<0.0001). The urine sum, which reflects the conversion of L-tryptophan→nicotinamide, correlated well with the activity of 3-hydroxyanthranilic acid dioxygenase (p=0.040). A nutritional indicator, the urine ratio (N(1)-methyl-2-pyridone-5-carboxamide + N(1)-methyl-4-pyridone-3-carboxamide)/N(1)-methylnicotinamide, was controlled by the activity of N(1)-methyl-2-pyridone-5-carboxamide-forming N(1)-methylnicotinamide oxidase.
authors.affiliation: Department of Nutrition, School of Human Cultures, The University of Shiga Prefecture.
authors.forename: Katsumi
authors.initials: K
authors.lastname: Shibata
authors.forename: Nobuya
authors.initials: N
authors.lastname: Morita
authors.forename: Yoshika
authors.initials: Y
authors.lastname: Shibata
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Fukuwatari
mesh_terms: D000818:Animals; D001835:Body Weight; D004435:Eating; D004798:Enzymes / Q000378:metabolism*; D008297:Male; D051379:Mice; D009243:NAD / Q000378:metabolism; D009536:Niacinamide / Q000031:analogs & derivatives* / Q000378:metabolism / Q000652:urine; D011728:Pyridones / Q000378:metabolism / Q000652:urine*; D017378:Quinolinic Acid / Q000378:metabolism; D014364:Tryptophan / Q000378:metabolism*
chemical_list: D004798:Enzymes; D011728:Pyridones; C503246:l-methyl-2-pyridone-5-carboxamide; D009243:NAD; D009536:Niacinamide; C016590:N(1)-methyl-4-pyridone-5-carboxamide; D014364:Tryptophan; D017378:Quinolinic Acid; C024058:N(1)-methylnicotinamide